CA1309978C

CA1309978C - Sorting apparatus for fiber suspensions

Info

Publication number: CA1309978C
Application number: CA 529998
Authority: CA
Inventors: Albrecht Meinecke; Walter Musselmann
Original assignee: JM Voith GmbH
Current assignee: JM Voith GmbH
Priority date: 1986-02-18
Filing date: 1987-02-18
Publication date: 1992-11-10
Anticipated expiration: 2009-11-10
Also published as: KR870008081A; FI86565C; EP0235605A2; NO169855B; EP0235605B1; ES2015545B3; JP2542206B2; NO870615D0; ATE53083T1; FI870548L; BR8701021A; NO870615L; EP0235605A3; US4880532A; KR950004725B1; FI86565B; JPS62191591A; DE3762896D1; NO169855C; FI870548A0

Abstract

Abstract of the Disclosure A sorting apparatus for fibrous suspensions includes a casing section with a larger diameter and a casing section with a relatively smaller diameter, the two following immediately one another. A rotor is present which features rotor parts which are coordinated with each casing section and appropriately adapted. An impeller rotates in the casing section, in a churning space, and a drum type rotor section is provided in the casing section, supporting sorting elements which rotate in a strainer space formed by a cylindrical strainer basket. This arrangement makes it possible to both despeckle and sort in the machine and separate the rejects at a high solid content.

Description

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Sorting Apparatus for Fiber Suspensions_ The invention concerns a sorting apparatus for fiber suspensions, particularly a so-called final stage sorter for the heavily contaminated rejects fractions in waste paper processing.
Such sorting apparatus are previously known from the U.S. Patent No. 3,898,157. This sorter was not developed as a final stage sorter because diluting water is added at the end of the second sorting zone and a very narrow discharge cross section exists there. Thus, it is not possible for rejects to leave the strainer zone at a high consistency. Moreover, it follows from the description in the patent that the concern is to en-able a high rate of production. Additionally, it is stated that specifically specks or knots are to be removed from the fiber suspension, which is basically indicative of the fact that, in relation to the heavily contaminated suspension accruing in the flnal stage, a relatively lightly contaminated fiber suspension is being processed.
The machine employed in the final stage of a sorting (for instance, sorting of waste paper) serves to separate interfering substances (rejects) from the usable fiber material. This separation process must be carried out in a way such that a fiber loss as low as possible will result and a rejects separation degree as high as possible will be achieved nevertheless. As is well known, the final sorting stage determines the efficiency of the entire sorting process.
Prior final stage sorters are, e.g., vibratory sorters. These machines require~ with the necessary strainer perforations, relatively large strainer surfaces and high fraction dilutions in order to achieve any reasonably satisfactory sorting effect at all.
Additionally, the strainers are very susceptible to clo~ging.~
Therefore, final stage sorters have been developed in~ recent years;which are designed to replace these vibratory sorters, and provide a rejects dry content as ' :
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high as possible, as described for instance in the German patent publication No. 3,006,482. Disadvantages of this machine are its use limitecl to only medium purity requirements and the relatively high energy consumption for strictly sorting purposes.
Another new final stage sorter is the rejects sorter according to the Serman patent publication No.
3,238,742. This machine also is strictly a sorter, that is, a beating of paper specks which are frequently contained in the fraction takes place only very ineffectually. With tightly ~small) perforated sorting strainers, the energy consumption is high as well and the material loss is often considerable.
The problem underlying the present invention is to provide a sorting apparatus where the rejects are separated in the final stage and the fiber loss is as low as possible, where a continuous operation and additionally a continuous removal of the light contaminations is possible and a high rejects consistency achievable.
In accordance with the present invention, there is provided a sorting apparatus for fiber suspensions with an essentially rotationally symmetric casing, which comprises two different rotationally symmetric casing sections extending into one another and having different diameters, of which the casing section with the larger diameter includes an essentially flat strainer ; essentially perpendicular to the rotationally symmetric axis of the casing sections, which strainer separates an accepts space from a churning space, and of which the casing section with the smaller diameter possesses a strainer basket which is arranged concentric with the casing section and which divides the casing section in a sortlng space and an accepts space, a rotor with an 35~ impeller coordinated with the casing section with the larger diameter, the sorting elements of which impeller rotate closely beside the strainer in the churning space, and ~a cylindrical component coordinated with the casing section with the smaller diameter which features ~ 3 ~
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on its circum~erence sorting elements which are constructed as sorting blades or slats, with the cylindrical component being radially enveloped by the strainer basket and the smaller casing section being essentially open at the ~ar end from the impeller, and with the inlet to the entire casing unit being provided to the churning space o~ the larger casing section.
The invention will be described further, by way of illustration, with reference to the accompanying drawings, in which:
Figure 1 is a longitudinal sectional view of a sorting apparatus provided in accordance with one embodiment of the invention;
Figure 2 is a modified form of the sorting structure apparatus of Figure 1;
Figures 3 and 3a are respectively longitudinal and cross-sectional views of a further modified form of the sorting apparatus of Figure l;
Figures 4 and ~a are respectively longitudinal and cross-sectional views of an additionally-modifisd form of the sorting apparatus of Figure l;
Figure 5 is a longitudinal sectional view of a ;~ modified final stage sorter; and Figure 6 is a longitudinal sectional view of a further modified final stage sorter.
Referring to the drawings, German patent publication No. 3,010,~52 describes a sorting apparatus featuring important details concerning the rotor component coordinated with the first casing section 1 with the larger diameter. But th~ design is not limited to these details. For the other rotor part coordinated with the second casing section 2 with the larger diameter, important details can be derived from 3~ the German patent publication No. 2,930,475. Possible embodiments are taught also in the previously cited German patent publication No. 3,006,482. Therefore, the ~ - :
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respective details of the rotor are merely indicated in the presentations. The machine includes a casing which is essentially cylindrical and a casing section 1 with a relatively large diameter D and a casing section 2 with a relatively small diameter d. The ratio of the casing diameters or strainer diameters, respectively, is D/d =
1.5 to 4. Since the radial pressure gradient in the casing section 1 is to be utilized here, the practical embodiments tend more toward the higher values. Th~ intake to the machine occurs at 3 essentially tangentially, at the circumference of the casing section 1, into a first strainer space which is constructed as a disk-shaped churning space 5 and in which the impeller component 7 of the rotor is arranged closely adjacent to th~ strainer 8. Located behind the strainer 8 is an accepts space 4 from which the cleaned fiber s~speDsion , :' , : .
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is rem~ved through the pipe socket 14. The ratio of the width ~ of the churning space 5 to the diameter D of the casing section 1 is preferably between 0.1 and 0.3, and the higher value should not be exceeded. The rotor 6 possesses a shaft 18 through which is supported at 19, and is powered by a motor 21.
The churning space 5 is followed by the strainer space 12 of the second casing section 2 which is formed between a drum type extension 9 of the rotor and a cylindrical strainer basket 11. The drum 9 supports sorting elements in the form of shapes or wings 12 whose contour is such that they extend radially only at a slight distance from the strainer basket 11. The sorting elements 16 preferably generate feed components toward the outlet end 17 of the strainer space so as to eject the rejects. The accepts which have passed through the perforations of the strainer basket 11 are removed through the pipe socket 20.
To increase the despeckling effect in the casing 1, slats, for instance in the form of welding beads, may be customarily provided on the strainer 8, on the far side from the impeller 7. An additional despeckling effect can be achieved through stator elements 15 which are arranged in annular fashion around the impeller.
In order to achieve a backup effect in the transition from the churning space 5 to the strainer space ~2~ a worm feed 28 is provided on the drum section 9 whose feed effect is chosen toward the strainer 8.
This provides sufficient time for despeckling the fiber bundles or for breaking up the paper shreds, respectively.
The holes of the perforation are selected, relative to the stralner 8, preferably between 1.0 and 3.0 mm diameter, and for the perforation of the strainer basket lI at 0.6 to 1.5 mm diameter or, in the case of slots, ; at 0.2 to 0.8 mm for the strainer 8 and at 0.15 to 0.8 mm for the strainer basket 11. The drum type section 9, in the direction from the front wall of the casing section l to the impeller 7, may be designed to have a : :

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decreasing diameter. This increases the radial pressure difference. The radial pressure difference causes the feeding or transition, respectively, of the suspension from the churning space 5 into the strainer space 12. In the process, preferably light contaminations accumulate in the center, that is, near the drum type section 9, which are separated directly by the casing section 2.
This is a major advantage because they do not remain for long in the churning space 5 and are thus unable to hinder the sorting operation, and since they are not comminuted themselves either.
Naturally, there is the further important advantage that only a single drive is needed whereas prior systems had to be equipped with several sorting apparatus which, of course, each required a drive of their own.
Advantageous is also that a practically continuous operation is achieved, in that wash water is passed through the lines and, as indicated by the dash-dot arrow, to the strainer space 12 so that the rejects can be continuously separated from the fiber portion and removed.
A simple control of the transition of the suspension from the churning space 5 to the strainer space 12 is provided through the speed of rotation of the rotor, which influences the radial pressure gradient. The pressure gradient may amount, e.g., to about 5 to 8 m water head so that, in the vicinity of the drum type section g, there prevails only a pressure of 1 to 2 m water head, when introducing the suspension at a pressure of approximately 1 bar at 3 in the casing section l. The feeding of the suspension takes place favorably ~angentially to the circumference. Similarly, the transitional pressure gradient can be influenced by the pressure level itself.
The rotor shaft preferably is arranged vertically, since the backup at the discharge end 17 of the drum section 9 then favorably influences the sorting effect or rejects separation, respectively, and a high dry content~of the discharged rejects can be achieved.

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The components with a high specific gravity, speclfically heavy contaminations, tend to accumulate on the periphery of the casing section 1. Therefore, a return line 31 is provided, as seen in Figure 2, which wlth the aid of valve 32 can be opened, for instance periodically, so as to return these dirt portions to the casing section 2. The line 31 empties into the casing section 2 behind a rotating disk 33 which separates the churning space 5 from the casing section 2. In this way, the heavy contaminations can be separated continuously as well, constituting a major advantage. Locks conventionally employed always involve a greater design expense and additional diluting water for cleaning the lock.
In the embodiment shown in Figures 3 and 3a, a swash plate 23 is provided which rotates in a small additional casing 29 and is attached to the drum section 9. This arrangement causes a backup effect because it transfe.rs the suspension at a dosed feed effect from the churning space 5 into the strainer 12. The additional ~ casing 29 is essentially a cylinder which, in its upper : area, is truncated at 29'. Using an ad~ustable-tilt swash plate 23 also accomplishes a regulation or : adaptation, respectively, to the conditions.
According to Figures 4 and 4a, a variant is ~ provided where a fixed disk and a rotating disk 24 with an appropriate cutout 26, as a rotating disk arrange-:~ ment, ensure a controlled changeover of the suspension.
The described sorting apparatus may be both the . 30 first coarse sorter stage within low daily productions and also a later coarse sorting stage at higher daily `~ productions. In the second case, it would then be arranged in a side circuit.
~ The application area of the sorting apparatus, :~ ~: 35 naturally, is not limited only to coarse sorting operations but rather the machine may be used also for ; medium fine sorting purposes. Fine sorting, naturally, takes place with the above-cited minimum values of the :strainer slots, or at least little above them.

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Figure 5 depicts a variant of the final stage sorter where the rotor 250 in the area of the second strainer 211 is of a hollow design featuring a circumferential wall 253 which is provided with water spray holes 52 for introducing diluting water into the second strainer space 212. The rotor shaft 218 is hollow, so that further diluting water can be introduced in the transitional area between the first strainer space 105 and the second strainer space 212. The rotor shaft has openings 80 for that purpose. The spray water is fed through a line 64.
As indicated by the dash-dot line, the spray water also may be fed under pressure, for instance by means of a spray water head 65 such as described, e.g., in German patent publication No. 3,006,482.
Moreover, the second strainer 211 is enlarged in diameter in its upper area, relative to its lower area, which a~plies also to the respective rotor section, so that the sorting elements 16 rotate here on a greater diameter at a higher peripheral speed, thereby exerting a better dehydrating effect on the rejects cake. A
centrifugal disk 62 discharges the rejects cake then into the rejects channel 60.
Illustrated additionally is a backup wall 71 which is coordinated with the accepts space 209 which is arranged behind the second strainer 211 and passes the accepts into an accepts removal chamber 72 from whence ,, it is then removed through a withdrawal line 73.
In the embodiment shown in Figure 6, the diameter enlargement oE the rotor section 50 coordinated with the second strainer space 112 has been achieved through a conic design of the upper part 154 of the rotor se~tion.
The sorting elements are constructed as hydrofoils 16' held by spacers 51 on the peripheral wall 153 of the drum. Spray water holes 52 are in this case preferably located directly in the area of these hydrofoils 16', and at that, preferably in the direction of rotation behind the spacers 51. A clogging of these spray water :;

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~3~78 holes can thereby be largely avoided when the spray water feeding is not taking place under pressure.
The rotor 107 of the first strainer space 205 has radia]ly outwardly despeckling elements 42 interacting with fixed despeckling elements 41 which preferably are constructed as ribs. Similar to Figure 1 and the preceding Figures, the rotor 107 is constructed as an impeller with individual radial or cycloidally shaped arms.
Ribs 44 now ensure a circulation of the suspension in the despeckling zone 40. To avoid excessive thickenlng, a recirculation of the fiber suspension is achieved through a line 46, to which additionally a water supply line 47 may be connected. A very extensive despeckling effect can be achieved thereby.
The removal of the accepts from the accepts space 109 following the second strainer space 112 is carried out through the line 77.
Through the successive arrangement of the strainer spaces directly at the rotors and adjacent to them, a very good fiber separation from the rejects and a high solid content of the rejects at the outlet of the sorting apparatus are possible. The consistency amounts to preferably more than 15 or 20~. The residual fiber content in the rejects is very low.
In summary of this disclosure, the present ` invention provides a novel sorting apparatus which is highly advantageous when compared with the prior art.
~odifications are possible within the scope of this invention.

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Claims

1. A sorting apparatus for fiber suspensions with an essentially rotationally symmetric casing, which comprises:
two different rotationally symmetric casing sections extending into one another and having different diameters, of which the casing section with the larger diameter includes an essentially flat strainer essentially perpendicular to the rotationally symmetric axis of the casing sections, which strainer separates an accepts space from a churning space, and of which the casing section with the smaller diameter possesses a strainer basket which is arranged concentric with the casing section and which divides the casing section into a sorting space and an accepts space;
control means controlling the changeover of suspension from a first straining space to a second straining space and constructed as a mechanical control arranged at the transition from one to the other casing section;
a rotor with an impeller coordinated with the casing section with the larger diameter, the sorting elements of which impeller rotate closely beside the strainer in the churning space;
a cylindrical component coordinated with the casing section with the smaller diameter which possesses on its circumference sorting elements which are constructed as sorting blades or slats, with the cylindrical component being radially enveloped by the strainer basket and the smaller casing section being essentially open on the far end from the impeller; and an inlet to the entire casing unit provided to the churning space of the larger casing section.

2. The sorting apparatus of claim 1, wherein, in the first strainer space, the ratio of the width to the diameter is about to 0.1 to 0.3.

3. The sorting apparatus of claim 1, wherein the rotor axis of rotation is arranged vertically and the second strainer space is arranged above the first one.

4. The sorting apparatus of claim 2 wherein the rotor axis of rotation is arranged vertically and the second strainer space is arranged above the first one.

5. The sorting apparatus of claim 1, 3 or 4, wherein the rotor shaft is of a hollow design to permit diluting water to be fed to the end of the second strainer space which is adjacent to the first strainer space.

6. The sorting apparatus of claim 2 wherein the rotor is of a hollow design to permit diluting water to be fed to the end of the second strainer space which is adjacent to the first strainer space.

7. The sorting apparatus of claim 1 wherein the diameter of the strainer of the second strainer space increases gradually or suddenly to the discharge end of the rejects fraction.

8. The sorting apparatus of claim 2 wherein the diameter of the strainer of the second strainer space increases gradually or suddenly to the discharge end of the rejects fraction.

9. The sorting apparatus of claim 3 wherein the diameter of the strainer of the second strainer space increases gradually or suddenly to the discharge end of the rejects fraction.

10. The sorting apparatus of claim 4 wherein the diameter of the strainer of the second strainer space increases gradually or suddenly to the discharge end of the rejects fraction.

11. The sorting apparatus of claim 6 wherein the diameter of the strainer of the second strainer space increases gradually or suddenly to the discharge end of the rejects fraction.

12. The sorting apparatus of claim 1, 2, 3, 4, 6, 8, 9, 10 or 11, wherein the mechanical control is constructed as a swash plate.

13. The sorting apparatus of claim 1, 2, 4 or 6, wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

14. The sorting apparatus of claim 3 wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

15. The sorting apparatus of claim 8 wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

16. The sorting apparatus of claim 9 wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

17. The sorting apparatus of claim 10 wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

18. The sorting apparatus of claim 11 wherein the mechanical control is a disk which controls the flow and hence the pressure drop.

19. The sorting apparatus of claim 14, wherein the rotating disk is adjustable.

20. The sorting apparatus of claim 15 wherein the rotating disk is adjustable.

21. The sorting apparatus of claim 16 wherein the rotating disk is adjustable.

22. The sorting apparatus of claim 17 wherein the rotating disk is adjustable.

23. The sorting apparatus of claim 18 wherein the rotating disk is adjustable.

24. The sorting apparatus of claim 1, 2, 3, 4, 6, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22 or 23, wherein the mechanical control comprises a rotating and a fixed perforated disk with openings coordinated with one another.

25. The sorting apparatus of claim 1, 2, 3, 4, 6, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22 or 23, , wherein the mechanical control is a worm feed.

26. The sorting apparatus of claim 14, the ratio of the diameter (D) of the strainer having the larger casing section to the diameter (d) of the strainer having the smaller casing section is D/d = 1.5 to 4.

27. The sorting apparatus of claim 15 wherein the ratio of the diameter (D) of the strainer having the larger casing section to the diameter (d) of the strainer having the smaller casing section is D/d = 1.5 to 4.

28. The sorting apparatus of claim 16 wherein the ratio of the diameter (D) of the strainer having the larger casing section to the diameter (d) of the strainer having the smaller casing section is D/d = 1.5 to 4.

29. The sorting apparatus of claim 17 wherein the ratio of the diameter (D) of the strainer having the larger casing section to the diameter (d) of the strainer having the smaller casing section is D/d = 1.5 to 4.

30. The sorting apparatus of claim 18 wherein the ratio of the diameter (D) of the strainer having the larger casing section to the diameter (d) of the strainer having the smaller casing section is D/d = 1.5 to 4.

31. The sorting apparatus of claim 26, 27, 28, 29 or 30 wherein, in the peripheral area of the first strainer space, radially outside the disk-shaped strainer, there is located a despeckling zone having despeckling elements arranged on the wall of the first strainer space, opposite the strainer, there are located deflector ribs for deflecting the flow of the fraction circulating in the despeckling zone, toward the strainer; a circulation line runs from the despeckling zone to said wall area, radially inside the ribs; and a water line is connected to the circulation line.

32. The sorting apparatus of claim 26, 27, 28, 29 or 30, wherein the sorting elements of the second strainer space are constructed as hydrofoils which are supported by spacer elements, and spray water holes are provided in the area of the sorting elements, in the direction of rotation behind the spacer elements, in the peripheral wall of the rotor of hollow design.